WO2009081810A1 - Display device having optical sensor - Google Patents

Display device having optical sensor

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Publication number
WO2009081810A1
WO2009081810A1 PCT/JP2008/072951 JP2008072951W WO2009081810A1 WO 2009081810 A1 WO2009081810 A1 WO 2009081810A1 JP 2008072951 W JP2008072951 W JP 2008072951W WO 2009081810 A1 WO2009081810 A1 WO 2009081810A1
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WO
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Application
Patent type
Prior art keywords
light
backlight
display device
sensor
mode
Prior art date
Application number
PCT/JP2008/072951
Other languages
French (fr)
Japanese (ja)
Inventor
Akizumi Fujioka
Akinori Kubota
Original Assignee
Sharp Kabushiki Kaisha
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

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Classifications

    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • G06F3/0412Integrated displays and digitisers
    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F1/00Details not covered by groups G06F3/00 – G06F13/00 and G06F21/00
    • G06F1/26Power supply means, e.g. regulation thereof
    • G06F1/32Means for saving power
    • G06F1/3203Power Management, i.e. event-based initiation of power-saving mode
    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F1/00Details not covered by groups G06F3/00 – G06F13/00 and G06F21/00
    • G06F1/26Power supply means, e.g. regulation thereof
    • G06F1/32Means for saving power
    • G06F1/3203Power Management, i.e. event-based initiation of power-saving mode
    • G06F1/3234Action, measure or step performed to reduce power consumption
    • G06F1/325Power saving in peripheral device
    • G06F1/3262Power saving in digitizer or tablet
    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • G06F3/042Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by opto-electronic means
    • GPHYSICS
    • G02OPTICS
    • G02FDEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH IS MODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THE DEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY, COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g. SWITCHING, GATING, MODULATING OR DEMODULATING; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • G02F1/13338Input devices, e.g. touch-panels
    • GPHYSICS
    • G02OPTICS
    • G02FDEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH IS MODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THE DEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY, COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g. SWITCHING, GATING, MODULATING OR DEMODULATING; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/13306Circuit arrangements or driving methods for the control of single liquid crystal cells
    • G02F2001/13312Circuits comprising a photodetector not for feedback
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2330/00Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/02Details of power systems and of start or stop of display operation
    • G09G2330/021Power management, e.g. power saving
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2360/00Aspects of the architecture of display systems
    • G09G2360/14Detecting light within display terminals, e.g. using a single or a plurality of photosensors
    • G09G2360/144Detecting light within display terminals, e.g. using a single or a plurality of photosensors the light being ambient light
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406Control of illumination source

Abstract

Provided is a display device having a plurality of optical sensors arranged on a display panel. The display panel can be operated by touching the panel with a finger or a pen. A liquid crystal panel (11) having built-in sensors includes a plurality of pixel circuits (1) and a plurality of optical sensors (2) which are arranged two-dimensionally. An MPU (18) selects a mode for detecting a shadow image of an object or a mode for detecting a reflected image of the object according to the illuminance of the outside light. One frame period is divided into a display period and a sensing period. A backlight (14) is controlled to be ON during the display period of the shadow mode and the sensing period of the reflected image mode and OFF during the sensing period of the shadow mode and the display period of the reflected image mode. Thus, it is possible to increase the detection accuracy of the touch position while suppressing the power consumption by the backlight.

Description

Display device with a photosensor

The present invention relates to a display device, and more particularly to a display device having a plurality of optical sensors on the display panel.

In recent years, operable electronic devices have become popular by touching the screen with a finger or a pen. Further, as a method of detecting a touch position on a display screen, a plurality of light sensors to the display panel, a method of detecting a shadow image that can be when a finger or the like approaches the screen using the light sensor is known.

Patent Document 1 In this connection, the backlight is lit in the display period for displaying display data on the display unit, wherein the display device to turn off the backlight sense period for reading the sensor output from the sensor It is. According to this display device, to reduce the influence of backlight light upon detecting a shadow image, it is possible to improve the detection accuracy of the optical sensor.

However, in the method of detecting a shadow image, when the illumination of outside light is low (dark ambient), to distinguish between a shadow image and a background in an image obtained by the optical sensor becomes difficult and can not be detected correctly touch position is there. Therefore, a display device having a backlight, a method of detecting using optical sensors the reflected image is devised when backlight light hits a finger.
Japanese Patent 2006-317682 JP

However, for backlight control for the case of using the method of detecting a reflection image, it is not devised specific method so far. Therefore, when the conventional as well as maintaining the brightness of the backlight, reduces the detection accuracy for a touch position when lowering the luminance, there is a problem that power consumption of the backlight is increased when increasing the brightness.

Therefore, the present invention provides a display device comprising a plurality of optical sensors, while suppressing the power consumption of the backlight, and an object thereof is to increase the detection accuracy for a touch position.

The first aspect of the present invention, there is provided a display device comprising a plurality of optical sensors,
A display panel including a plurality of pixel circuits and a plurality of optical sensors which are arranged two-dimensionally,
A drive circuit that drives the display panel,
A backlight that irradiates light on the back of the display panel,
When detecting a reflection image of the object, said light sensing period for reading the signals from the sensor, the backlight so that the amount of light detected by the light sensor than the display period for writing a signal to the pixel circuit is increased controlling the and a backlight control unit.

The second aspect of the present invention, in the first aspect of the present invention,
Or shadow image mode that detects a shadow image of the object, further comprising an operation mode selection unit for selecting whether the reflection image mode that detects a reflection image of the object,
The backlight control unit, when the reflection image mode is selected, the sensing period and controls the backlight such that the amount of light detected by the optical sensor is larger than the display period.

A third aspect of the present invention, in the second aspect of the present invention,
The backlight control unit, when the reflection image mode is selected, the sensing period and controls the backlight such that the luminance is higher than the display period.

A fourth aspect of the present invention, in the third aspect of the present invention,
The backlight control unit, when the shadow image mode is selected, the sensing period and controls the backlight such that the luminance is lower than the display period.

A fifth aspect of the present invention, in the second aspect of the present invention,
The backlight includes a plurality of colors of light sources,
The backlight control unit, and controls the lighting state of the light source based on the light properties of the light sensor.

The sixth aspect of the present invention, in the fifth aspect of the present invention,
The backlight control unit, when the reflection image mode is selected, a sensing period, characterized in that it is turned with priority color of the light source a high light reception sensitivity of the optical sensor.

Seventh aspect of the present invention, in the sixth aspect of the present invention,
The backlight control unit, when the shadow image mode is selected, a sensing period, characterized in that it is turned with priority color of the light source the light receiving sensitivity is low the light sensor.

Eighth aspect of the present invention, in the second aspect of the present invention,
Further comprising an illuminance sensor for detecting the illuminance of outside light,
The mode selecting unit, based on the illuminance detected by the illuminance sensor, and selects whether shadow image mode or the reflection image mode.

Ninth aspect of the present invention, in the second aspect of the present invention,
Further comprising a characteristic detecting unit that obtains a characteristic of display data supplied to the display panel,
The mode selecting unit, based on the determined characteristics in the characteristic detector, and selects whether shadow image mode or the reflection image mode.

Tenth aspect of the present invention, in the ninth aspect of the present invention,
The characteristic extraction unit, as a characteristic of the display data, and obtains the amount of light sensitive color of the light sensor.

11th aspect of the present invention, irradiation and display panel including a plurality of pixel circuits and a plurality of optical sensors which are arranged two-dimensionally, a driving circuit for driving the display panel, the light on the back of the display panel a method of driving a display device including a backlight that,
Using the drive circuit, and writing the signal to the pixel circuit,
A step of using said drive circuit reads the signal from the light sensor,
When detecting a reflection image of the object, said light sensing period for reading the signals from the sensor, the backlight so that the amount of light detected by the light sensor than the display period for writing a signal to the pixel circuit is increased controlling the and a step.

According to the first or eleventh aspect of the present invention, when detecting a reflection image of the object, by the sensing period to increase the amount of light (reflected light) detected by the optical sensors than the display period, while suppressing the power consumption of the backlight, by increasing the brightness of the reflected image, it is possible to increase the detection accuracy for a touch position.

According to a second aspect of the present invention, as well as select a preferred mode of operation depending on the situation, in the sensing period of the reflection image mode increase the amount of light (reflected light) detected by the optical sensors than the display period by while suppressing the power consumption of the backlight, by increasing the brightness of the reflected image, it is possible to increase the detection accuracy for a touch position of the reflection image mode.

According to a third aspect of the present invention, by the sensing period of the reflection image mode to increase the luminance of the backlight than the display period, is possible to increase the amount of light (reflected light) detected by the optical sensors it can. Thus, while suppressing the power consumption of the backlight, by increasing the brightness of the reflected image, it is possible to increase the detection accuracy for a touch position of the reflection image mode.

According to a fourth aspect of the present invention, in the sensing period of the shadow image mode by lowering the luminance of the backlight than the display period, it is possible to reduce the amount of light detected by the light sensor. This reduces the influence of backlight light upon detecting a shadow image, it is possible to increase the detection accuracy for a touch position of the shadow image mode.

According to a fifth aspect of the present invention, by controlling the lighting state of a plurality of colors of light sources based on the light properties of the light sensor, the light reception sensitivity of the optical sensors suitably controlled depending on the situation, the touch position it is possible to improve detection accuracy.

According to a sixth aspect of the present invention, by lighting with priority color of the light source a high light reception sensitivity of the optical sensor in the sensing period of the reflection image mode, the amount of light (reflected light) detected by the optical sensors it is possible to increase the. Thus, while suppressing the power consumption of the backlight, by increasing the brightness of the reflected image, it is possible to increase the detection accuracy for a touch position of the reflection image mode.

According to a seventh aspect of the present invention, by lighting with priority color of the light source light it is less sensitive photosensors in the sensing period of shadow image mode, is possible to reduce the amount of light detected by the light sensor it can. This reduces the influence of backlight light upon detecting a shadow image, it is possible to increase the detection accuracy for a touch position of the shadow image mode.

According to an eighth aspect of the present invention, easily detecting a shadow image when the illumination of outside light is high, when the illumination of outside light is low, in consideration of difficult to detect a shadow image, suitable based on the illumination of outside light select the operating mode, while suppressing the power consumption of the backlight, it is possible to increase the detection accuracy for a touch position.

According to a ninth aspect of the present invention, it is possible to select the preferred operation mode based on the characteristics of the display data, while suppressing the power consumption of the backlight, increase the detection accuracy for a touch position.

According to a tenth aspect of the present invention, easily detecting a shadow image when the amount of received light sensitive color light sensor is small, when the amount is large in consideration hard to detecting a shadow image, the light receiving sensitivity of the optical sensor select the preferred operation mode based on the amount of high color, while suppressing the power consumption of the backlight, it is possible to increase the detection accuracy for a touch position.

Is a block diagram showing a configuration of a liquid crystal display device according to a first embodiment of the present invention. It is a block diagram showing the structure and peripheral circuits of the liquid crystal panel of the device shown in FIG. Is a diagram showing an arrangement position of the cross section and the back light of a liquid crystal panel of the device shown in FIG. Is a diagram showing the principle of the method of detecting a shadow image in the device shown in FIG. Is a diagram showing the principle of the method of detecting a reflection image in the device shown in FIG. It is a flowchart showing a touch position detection process performed by the apparatus shown in FIG. Is a table showing backlight control performed by the apparatus shown in FIG. It is a timing chart of the device shadow image mode shown in FIG. It is a timing chart of the reflection image mode of the device shown in FIG. It is a diagram showing a first example of a scanned image including a finger image. It is a diagram showing a second example of a scanned image including a finger image. It is a diagram showing a third example of a scanned image including a finger image. It is a diagram showing a fourth example of a scanned image including a finger image. It is a block diagram showing a configuration of a liquid crystal display device according to a second embodiment of the present invention. Is a table showing backlight control performed by the apparatus shown in FIG. It is a timing chart of the device shadow image mode shown in FIG. It is a timing chart of the reflection image mode of the device shown in FIG. It is a block diagram showing a configuration of a liquid crystal display device according to a third embodiment of the present invention. It is a flowchart showing a touch position detection process performed by the apparatus shown in FIG. 12.

DESCRIPTION OF SYMBOLS

1 ... pixel circuit 2 ... optical sensors 6 ... photodiode 10, 20, 30 ... liquid crystal display device 11 ... liquid crystal panel with built-in sensors 12 ... panel driving circuit 13, 23 ... backlight power supply circuit 14, 24 ... backlight 15 ... A / D converter 16, 36 ... image processing unit 17 ... illumination sensor 18,28,38 ... microprocessor unit (MPU)
19,29 ... LED
41 ... scanning signal line drive circuit 42 ... data signal line drive circuit 43 ... sensor row drive circuit 44 ... sensor output amplifiers 45-48 ... Switch 61 ... external light 62 ... backlight 63 ... object

(First Embodiment)
Figure 1 is a block diagram showing a configuration of a liquid crystal display device according to a first embodiment of the present invention. The liquid crystal display device 10 shown in FIG. 1, the sensor-equipped liquid crystal panel 11, the panel drive circuit 12, a backlight power supply circuit 13, a backlight 14, A / D converter 15, and an image processing unit 16, the illuminance sensor 17, a micro processor unit (hereinafter, MPU hereinafter) and a 18.

Liquid crystal panel with built-in sensors 11 (hereinafter, referred to as a liquid crystal panel 11) includes a plurality of light sensors and a plurality of pixel circuits arranged two-dimensionally (details will be described later). The liquid crystal display device 10, the display data Din is input from the outside. Input display data Din is supplied via the image processing unit 16 to the panel driving circuit 12. Panel drive circuit 12 writes voltages according to the display data Din into the pixel circuits of the liquid crystal panel 11. Thus, the liquid crystal panel 11 displays an image based on the display data Din.

The backlight 14 includes a plurality of white LED (Light Emitting Diode) 19, is irradiated with light (backlight light) to the back of the liquid crystal panel 11. Backlight power supply circuit 13 in accordance with the backlight control signal BC outputted from the MPU 18, switches whether to supply a power supply voltage to the backlight 14. Hereinafter, a backlight power supply circuit 13, the backlight control signal BC is supplying the power supply voltage is at the high level, the backlight control signal BC is at a low level shall not supply the power supply voltage. The backlight 14, while the backlight control signal BC is at a high level on, while the backlight control signal BC is at a low level to turn off.

The liquid crystal panel 11 outputs an output signal of the light sensor as a sensor output signal SS. A / D converter 15 converts the sensor output signal SS of the analog to digital signals. The image processing unit 16, based on the digital signal output from A / D converter 15, generates a digital image (hereinafter, referred to as a scanned image). The scanned image, the object to be detected in the vicinity of the surface of the liquid crystal panel 11 (e.g., a finger or a pen. Hereinafter referred object) may contain images of. So the image processing unit 16 performs an image recognition process on the scanned image to determine the position of the object within the scanned image. MPU18, based on the image recognition result by the image processing section 16 obtains and outputs coordinate data Cout indicating the touch position.

Illumination sensor 17 detects the illuminance of external light and outputs the illuminance data LX indicating the detected illuminance. Illuminance sensor 17, the backlight light is arranged so as not incident on the light receiving surface. MPU18, based on the illuminance data LX, mode of detecting a shadow image of the object (hereinafter, referred to as shadow image mode) or a mode that detects a reflection image of the object (hereinafter, referred to as reflection image mode) or to select. The reflection image mode may be detected only reflection image of the object, it may be detected both a shadow image and a reflection image of the object. Below, the selected mode of the operation mode MD in MPU18.

MPU18, based on the operation mode MD, performs backlight control. In the liquid crystal display device 10, one frame time is divided into a display period for writing a signal (voltage signal corresponding to the display data Din) to the pixel circuits, in the sensing period from the optical sensor reads out the signal (voltage signal corresponding to the light amount) It is. MPU18, for the display period and the sensing period, switching between the turn off or turn on the backlight 14 in accordance with the operation mode MD. Further, the operating mode MD is outputted to the image processing unit 16 from the MPU 18, the image processing unit 16 switches the algorithm of image recognition processing in accordance with the operation mode MD. Incidentally, MPU 18 may perform all or a part of the image recognition processing.

Figure 2 is a block diagram showing the structure and peripheral circuits of the liquid crystal panel 11. 2, the liquid crystal panel 11, m scanning signal lines G1 ~ Gm, 3n data signal lines SR1 ~ SRn, SG1 ~ SGn, SB1 ~ SBn, and, (m × 3n) pixels and it includes a circuit 1. Liquid crystal panel 11 in addition includes (m × n) pieces of light sensor 2, m the sensor read lines RW1 ~ RWm, and the sensor reset lines RS1 ~ RSm of the m. The liquid crystal panel 11 is formed using CG (Continuous Grain) silicon.

Scanning signal lines G1 ~ Gm are arranged parallel to one another. Data signal lines SR1 ~ SRn, SG1 ~ SGn, SB1 ~ SBn are arranged parallel to each other so as to be orthogonal to the scanning signal lines G1 ~ Gm. Sensor read lines RW1 ~ RWm and the sensor reset lines RS1 ~ RSm are arranged parallel to the scanning signal lines G1 ~ Gm.

The pixel circuit 1, the scanning signal lines G1 ~ Gm and the data signal lines SR1 ~ SRn, SG1 ~ SGn, SB1 is provided one by one near the intersection of ~ SBn. Pixel circuits 1, each m pieces in a column direction (in FIG. 2 the vertical direction), the row direction (lateral direction in FIG. 2) 3n pieces each, are located throughout as a two-dimensional shape. The pixel circuit 1, depending on the color of a color filter provided, R pixel circuits 1r, are classified into G pixel circuits 1g, and B pixel circuits 1b. 3 types of pixel circuits 1r, 1 g, 1b are arranged side by side in the row direction to form one pixel of three.

The pixel circuit 1 includes a TFT (Thin Film Transistor) 3 and a liquid crystal capacitance 4. The gate terminal of the TFT3 scanning signal line Gi (i is an integer 1 or m) are connected to the source terminal is connected to the data signal line SRj, SGj, to any of SBj (j is an integer from 1 to n) and a drain terminal connected to one electrode of the liquid crystal capacitance 4. The other electrode of the liquid crystal capacitance 4, the common electrode voltage is applied. Hereinafter, the connected data signal line SG1 ~ SGn the G pixel circuits 1 g G data signal lines, the connection data signal lines SB1 ~ SBn the B pixel circuits 1b as the B data signal lines. Note that the pixel circuits 1 may include an auxiliary capacitance.

The light transmittance of the pixel circuits 1 (the luminance of the sub-pixel) is determined by the voltage written into the pixel circuits 1. Scanning signal line Gi and the data signal line Sxj (X is one of R, G, B) in order to write a voltage in a pixel connected circuit 1, the high-level voltage (TFT 3 to the ON state to the scanning signal line Gi applying a voltage) to, or by applying a voltage to be written to the data signal line Sxj. By writing a voltage according to display data Din into the pixel circuits 1, it is possible to set the brightness of the sub-pixel to a desired level.

Light sensor 2 includes a capacitor 5 includes a photodiode 6, and a sensor preamplifier 7, is provided for each pixel. One electrode of the capacitor 5 is connected to the cathode terminal of the photodiode 6 (hereinafter, this connection point of the node A). The other electrode of the capacitor 5 is connected to the sensor read line RWi, the anode terminal of the photodiode 6 is connected to the sensor reset line RSi. Sensor preamplifier 7 is connected to a gate terminal to the node A, the drain terminal is connected to the B data signal line SBj, composed of TFT whose source terminal is connected to the G data signal line SGj.

To detect the amount of light in the sensor read line RWi and B data signal line connection etc. SBj light sensor 2, a predetermined voltage is applied to the sensor read line RWi and the sensor reset line RSi, the B data signal line SBj the power supply voltage VDD may be applied. After a predetermined voltage is applied to the sensor read line RWi and the sensor reset line RSi, when the photodiode 6 light incident, a current corresponding to the amount of incident light flows through the photodiode 6, minute current flowing voltage of the node A only to decrease. Upon application of a power supply voltage VDD to the B data signal line SBj, the voltage at node A is amplified by the sensor preamplifier 7, the G data signal line SGj the amplified voltage is outputted. Therefore, based on the voltage of the G data signal line SGj, it is possible to determine the amount of light detected by the optical sensor 2.

Around the liquid crystal panel 11, the scanning signal line drive circuit 41, the data signal line drive circuit 42, a sensor row drive circuit 43, p-number sensor output amplifiers 44 (p is an integer from 1 to n), and a plurality of switch 45 to 48 is provided. Scanning signal line drive circuit 41, the data signal line drive circuit 42 and the sensor row drive circuit 43 correspond to the panel drive circuit 12 in FIG. 1.

Data signal line drive circuit 42 has 3n output terminals for the respective 3n data signal lines. Switch 45 is provided between the G data signal lines SG1 ~ SGn and n output terminals corresponding thereto are provided one by one, B data signal lines SB1 ~ SBn and the n output terminals corresponding thereto switch 46 is provided one each between. G data signal lines SG1 ~ SGn are divided into groups of p present, k-th in the group (k is 1 or more p an integer) of the input terminals of the G data signal line and the k-th sensor output amplifier 44 switch 47 is provided one each between. B data signal lines SB1 ~ SBn are both connected to one end of the switch 48, the other end of the switch 48 the power supply voltage VDD is applied. Number of switches 45-47 which are contained in Figure 2 is of n, the number of switches 48 is one.

The circuit shown in Figure 2, operate differently in the display period and the sensing period. In the display period, the switches 45 and 46 turned on, the switch 47 and 48 is turned off. During the sensing period the contrary, the switch 45 and 46 turned off, the switch 48 is turned on, the switch 47 is such that the G data signal lines SG1 ~ SGn are connected to the input terminals of the sensor output amplifiers 44 in the order for each group It turned on by the two-time division.

In the display period, the scanning signal line drive circuit 41 and the data signal line drive circuit 42 is operated. Scanning signal line drive circuit 41 is applied according to a timing control signal C1, selects one scanning signal line for each line time from the scanning signal lines G1 ~ Gm, a high level voltage to the selected scanning signal line and, the remaining scanning signal line and applies a low-level voltage. Data signal line drive circuit 42, based display data DR outputted from the image processing unit 16, DG, the DB, and driving the data signal lines SR1 ~ SRn, the SG1 ~ SGn, SB1 ~ SBn by a line sequential system. More specifically, the data signal line drive circuit 42, the display data DR, DG, and stores by at least one row of DB, the voltage data signal lines SR1 ~ corresponding to the display data of one line for each line time SRn, SG1 applied to the ~ SGn, SB1 ~ SBn. Note that the data signal line drive circuit 42, the data signal lines SR1 ~ SRn, SG1 ~ SGn, SB1 ~ SBn may be driven by a dot sequential system a.

During the sensing period, the sensor row drive circuit 43 and the sensor output amplifiers 44 operate. Sensor row drive circuit 43 in accordance with the timing control signal C2, the signal line for each line time from the sensor read lines RW1 ~ RWm and the sensor reset lines RS1 ~ RSm selected one by one, the selected sensor read line and sensor the reset line by applying a predetermined voltage and a reset voltage for reading, the other signal line applies a voltage different from the time of selection. Note that typically, in the display period and the sensing period, the different length of one line time. Sensor output amplifier 44 amplifies the voltage selected by the switch 47, and outputs as a sensor output signal SS1 ~ SSp.

Figure 3 is a diagram showing an arrangement position of the cross section and the backlight 14 of the liquid crystal panel 11. The liquid crystal panel 11 has a structure sandwiching the liquid crystal layer 52 between two glass substrates 51a, 51b. One glass substrate 51a to the three color filters 53r, 53 g, 53b, the light-shielding film 54 is provided with such counter electrode 55, the other glass substrate 51b pixel electrode 56, the data signal line 57, such as an optical sensor 2 It is provided. As shown in FIG. 3, a photodiode 6 included in an optical sensor 2 is provided near the pixel electrode 56 having a blue color filter 53b (the reason will be described later). Glass substrate 51a, the opposing surfaces of 51b are provided alignment film 58, polarizer 59 is provided on the other surface. Becomes the surface of the glass substrate 51a side of the two plane surfaces of the liquid crystal panel 11, the surface of the glass substrate 51b side becomes the back. The backlight 14 is provided on the back side of the liquid crystal panel 11.

The liquid crystal display device 10, when detecting the touch position in the LCD screen, the method and the reflected image detecting a shadow image (or both a shadow image and a reflection image) is used by switching the method of detecting. 4A is a diagram showing the principle of the method of detecting a shadow image, FIG. 4B is a diagram showing the principle of a method of detecting a reflection image. In a method of detecting a shadow image (Fig. 4A), an optical sensor 2 including a photodiode 6 detects outside light 61 having passed through the such as a glass substrate 51a and a liquid crystal layer 52. When object 63 such as a finger in this case is in the vicinity of the surface of the liquid crystal panel 11, the outside light 61 to be incident on the optical sensor 2 is blocked by the object 63. Thus, using the optical sensor 2 can detect a shadow image of the object 63 by the outside light 61.

In a method of detecting a reflection image (Fig. 4B), an optical sensor 2 including a photodiode 6 detects reflected light of backlight light 62. More specifically, the backlight light 62 emitted from the backlight 14 exits to the outside from the surface of the liquid crystal panel 11 passes through the liquid crystal panel 11. When the object 63 in this case is in the vicinity of the surface of the liquid crystal panel 11, backlight 62 is reflected by the object 63. For example, belly of a human finger reflects light well. The reflected light of backlight light 62 is transmitted through the glass substrate or the like 51a and a liquid crystal layer 52 enters the optical sensor 2. Thus, using the optical sensor 2 can detect a reflection image of the object 63 by the backlight light 62.

Further, when combined with the two methods, it is possible to detect both a shadow image and a reflection image. That is, using the optical sensor 2 can detect the image of the object 63 by the outside light 61 and a reflection image of the object 63 by the backlight light 62 at the same time.

When the liquid crystal panel 11 in CG silicon, the light reception sensitivity of the photodiodes 6 is high for blue light, low in the red or green light. Therefore, in order to subject to blue light, a photodiode 6, as shown in FIG. 3, it is provided in the vicinity of the pixel electrode 56 corresponding to the blue color filter 53b. By arranging the photodiode 6 in this manner photosensitivity susceptible to high color light position, and increase the amount of light detected by the photodiode 6, it is possible to increase the light receiving sensitivity of the optical sensor 2.

Figure 5 is a flowchart showing a touch position detection process performed by the liquid crystal display device 10. The process shown in FIG. 5, the image processing unit 16 and the MPU18 performed every frame time. First, with respect to the illuminance sensor 17 MPU 18, the illuminance data LX representing the illumination of outside light is inputted (step S11). Then, MPU 18, based on the illuminance data LX, selects the operation mode MD (step S12). In step S12, the illuminance of the external light shadow image mode is selected when the predetermined threshold value or more, the reflection image mode is selected when the illumination of outside light is less than the threshold value.

Then, MPU 18 in accordance with the operation mode MD, and controls the backlight 14 (step S13). In step S13, backlight control shown in FIG. 6 is performed. MPU18, when the shadow image mode, the backlight is lit 14 during the display period, turns off the backlight 14 during the sensing period. When the reflection image mode cope with this, MPU 18, in the display period turns off the backlight 14, the backlight is turned 14 during the sensing period. MPU18 sets the backlight control signal BC to a high level when turning on the backlight 14, when turning off the backlight 14 sets the backlight control signal BC to a low level.

Next, the image processing unit 16, a digital signal output from A / D converter 15 is input (step S14). Next, the image processing unit 16 based on the input digital signal to generate a scanned image (step S15). Next, the image processing unit 16, to the scanned image, performs image recognition processing corresponding to the operation mode MD (step S16). In step S16, when the shadow image mode is performed processing for recognizing a shadow image, processing for recognizing a reflection image (or both a shadow image and a reflection image) is performed when the reflection image mode. Then, MPU 18, based on the image recognition result by the image processing unit 16 obtains the coordinate data Cout indicating the touch position, and outputs to the outside of the liquid crystal display device 10 (step S17). Thus MPU18 the operation mode selection unit for selecting whether shadow image mode or the reflection image mode, and functions as a backlight control unit that controls the backlight 14 according to the operation mode.

7A is a timing chart of the shadow image mode of the liquid crystal display device 10, FIG. 7B is a timing chart of the reflection image mode of the liquid crystal display device 10. In Figure 7A and Figure 7B, waveforms other than the backlight control signal BC is the same. As shown in FIGS. 7A and 7B, a vertical synchronizing signal VSYNC goes high every frame time, one frame time is divided into a display period and a sensing period. The sense signal SC is a signal indicating whether the display period or the sensing period, becomes low level during the display period, the high level during the sensing period.

In the display period, the switches 45 and 46 are turned on, both the data signal lines SR1 ~ SRn, SG1 ~ SGn, SB1 ~ SBn are connected to the data signal line drive circuit 42. In the display period, the voltage of the scanning signal line G1 goes high first, then becomes voltage high level of the scanning signal line G2, the voltage of the scanning signal lines G3 ~ Gm are sequentially become high level thereafter. During the voltage of the scanning signal line Gi is at a high level, the data signal lines SR1 ~ SRn, SG1 to the ~ SGn, SB1 ~ SBn, voltage to be written into 3n pixel circuits 1 connected to the scanning signal line Gi is applied It is.

In the sensing period, the switch 48 is turned on, the switch 47 is turned on in a time-division. Therefore, the B data signal lines SB1 ~ SBn supply voltage VDD is fixedly applied, G data signal lines SG1 ~ SGn are connected to the input terminals of the sensor output amplifiers 44 in a time-division. During the sensing period, first sensor read line RW1 and the sensor reset line RS1 are selected, then the sensor read line RW2 and the sensor reset line RS2 are selected and thereafter the sensor read lines RW3 ~ RWm and the sensor reset lines RS3 ~ RSm one set is selected in the order. The selected sensor read line and sensor reset line, respectively, read voltage and a reset voltage is applied. While the sensor read line RWi and the sensor reset line RSi are selected, the G data signal lines SG1 ~ SGn, a voltage corresponding to the amount of light detected by the n optical sensors 2 connected to the sensor read line RWi is output.

In shadow image mode (Fig. 7A), the backlight control signal BC will become high level during the display period, the low level during the sensing period. In this case, the backlight 14 is lit in the display period and turns off in the sensing period. In the reflection image mode (Fig. 7B) with respect to this, the backlight control signal BC is set to a low level during the display period, the high level during the sensing period. In this case, the backlight 14 is turned off in the display period, lights in the sensing period.

Hereinafter will be described the effects of the liquid crystal display device 10 according to the present embodiment. Figure 8A ~ 8D are diagrams showing an example of a scanned image including a finger image. Figure 8A shows a scanned image in the case where the backlight is lit when the illumination of outside light is high, Fig. 8B shows a scanned image when the illumination of outside light was turned off the backlight when high, FIG. 8C denotes the scan image when the illumination of outside light is lit backlight when low, Figure 8D shows a scanned image when the illumination of outside light is dark the backlight is lit when low.

As shown in FIGS. 8A and 8B, when the illumination of outside light is high, the scan image is obtained including the dark finger image (shadow image by the outside light) in a bright background. When the backlight is turned on this time (Fig. 8A), since the backlight light is reflected by the ball of the finger, the portion corresponding to the ball of the finger becomes brighter to the same extent as the background in the scanned image. Thus, the finger in the scanned image (in particular, a finger tip portion) the boundary between the background becomes unclear, the detection accuracy for a touch position decreases. Therefore, the liquid crystal display device 10 selects the shadow image mode when the illumination of outside light is high, turns off the backlight 14 during the sensing period (Fig. 8B). Thus, the portion corresponding to the ball of the finger in the scanned image becomes dark, correctly recognize the image of the finger (imaging) among bright background, it is possible to increase the detection accuracy for a touch position.

On the other hand, as shown in FIG. 8C and FIG. 8D, when the illumination of outside light is low, the scan image is obtained that includes an image of a dark finger in a dark background. When turning off the back light at this time, the distinction between the finger and the background in the scanned image becomes difficult, it can not be almost to detect a touch position. Therefore, the liquid crystal display device 10 selects the reflection image mode when the illumination of outside light is low, turns on the backlight 14 during the sensing period (Fig. 8C). At this time, since backlight light reflects off the ball of the finger, the portion corresponding to the ball of the finger becomes bright in the scanned image. Therefore, it is possible to darker abdominal image of the finger (reflection image) is recognized properly even in the background, increase the detection accuracy for a touch position.

For illumination of outside light increases the detection accuracy for a touch position when low, it is preferable luminance of the backlight is high. For example, when the dark the backlight is lit is the scan image shown in FIG. 8D is obtained, for the scan image of the ball of the finger image (reflection image) is small, it is difficult to correctly detect a touch position is there. However, increasing the luminance of the backlight, a problem that power consumption of the backlight is increased occurs. Therefore, the liquid crystal display device 10 turns off the backlight 14 during the display period of the reflection image mode. Thus, while maintaining the detection accuracy for a touch position, it is possible to reduce the power consumption of the backlight.

As described above, the liquid crystal display device 10 according to this embodiment selects whether shadow image mode or the reflection image mode, based on the illumination of outside light, and performs backlight control and an image recognition processing corresponding to the operation mode. Thus, the backlight 14 is lit during the sensing period in the display period and the reflection image mode of shadow image mode is controlled to be turned off in the display period of the sensing period and the reflection image mode of shadow image mode.

Therefore, when the illumination of outside light is low, selects the reflection image mode, the sensing period by increasing the luminance of the backlight 14 than the display period, the amount of light (reflected light) detected by the optical sensors 2 it can be increased. Thus, while suppressing the power consumption of the backlight 14, to increase the brightness of the reflected image, it is possible to increase the detection accuracy for a touch position of the reflection image mode. When the illumination of outside light is high against this, select the shadow image mode, the sensing period by lowering the luminance of the backlight 14 than the display period, it is possible to reduce the amount of light detected by the optical sensors 2 it can. This reduces the influence of backlight light upon detecting a shadow image, it is possible to increase the detection accuracy for a touch position of the shadow image mode. Thus selecting a preferred mode of operation based on the illumination of outside light, while suppressing the power consumption of the backlight 14, it is possible to increase the detection accuracy for a touch position.

The liquid crystal display device (hereinafter, referred to as conventional device) brightness of the backlight in the display period and the sensing period is the same in comparison with, specifically explaining the effects of the above. To detect a reflection image at the same accuracy as the conventional device in the liquid crystal display device 10, the luminance of the backlight 14 in the sensing period of the reflection image mode may be set to the same level as the conventional device. On the other hand, in the liquid crystal display device 10, the luminance of the backlight 14 is controlled lower than the sensing period in the display period of the reflected image mode. Therefore, according to the liquid crystal display device 10, while detecting a reflection image at the same accuracy as the conventional device, it is possible to reduce the power consumption of the backlight 14. However, in this case, the brightness of the display screen of the liquid crystal display device 10 is lower than the conventional device.

Therefore, as the brightness of the display screen is not reduced, it may increase the brightness of the backlight 14 than a liquid crystal display device 10 in the conventional device. In this case, the luminance of the backlight 14 in the sensing period of the reflection image mode because higher than the conventional apparatus, it is possible to detect a clear reflected image than conventional devices using an optical sensor 2. Therefore, according to the liquid crystal display device 10, without increasing the power consumption of the backlight 14, it is possible to increase the detection accuracy for a touch position than a conventional device.

In the above description, the liquid crystal display device 10, it is assumed that turning off the backlight 14 during the display period of the reflection image mode and sensing period of shadow image mode, the display period of the reflection image mode and sensing period of shadow image mode it may dim the backlight is lit 14. In general, it in the sensing period of the shadow image mode and controlling the backlight such that the luminance is lower than the display period, the sensing period of the reflection image mode for controlling the backlight such that the luminance is higher than the display period Accordingly, while suppressing the power consumption of the backlight, it is possible to increase the detection accuracy for a touch position.

(Second Embodiment)
Figure 9 is a block diagram showing a configuration of a liquid crystal display device according to a second embodiment of the present invention. The liquid crystal display device shown in FIG. 9 20, in the liquid crystal display device 10 according to the first embodiment (FIG. 1), the backlight power supply circuit 13, a backlight 14 and MPU18 backlight power supply circuit 23, a backlight 24 and MPU28 it is replaced with those which are. Among the elements in this embodiment, the same components as those of the first embodiment, its description is omitted with the same reference numerals.

The backlight 24 includes red LED29r, green LED29g and blue LED29 by plurality. Three LED29r, 29g, 29b are controlled to light by a predetermined time order within one frame time. Backlight power supply circuit 23, three backlight control signals BCr output from MPU 28, BCG, according BCb, red LED29r, switches whether the individual supplying the power supply voltage green LED29g and blue LED29b. Backlight power supply circuit 23 supplies power supply voltage for red LED29r when the backlight control signal BCr is high, does not supply a power supply voltage to the red LED29r when the backlight control signal BCr is low. Red LED29r is between the backlight control signal BCr is at a high level on, while the backlight control signal BCr is at a low level to turn off. Green LED29g blue LED29 also the same as this.

The image processing unit 16 and the MPU28 performs a touch position detection process shown in FIG. However, in step S13, backlight control shown in FIG. 10 is performed. Figure 11A is a timing chart of the shadow image mode of the liquid crystal display device 20, FIG. 11B is a timing chart of the reflection image mode of the liquid crystal display device 20. In Figure 11A and 11B, the backlight control signal BCr, BCG, the waveform of the non BCb the same.

In shadow image mode (Fig. 11A), MPU 28 is the backlight control signal BCb the display period is set to turn the high level by a predetermined time BCG, in the sensing period sets the backlight control signal BCr high level. Therefore, in the display period blue LED29r and green LED29g lights by a predetermined time, the red LED29r is turned in the sensing period. In the reflection image mode (Fig. 11B) relative to this, MPU 28 is the backlight control signal BCr the display period is set to turn the high level by a predetermined time BCG, a high level of the backlight control signal BCb the sensing period set to. Therefore, in the display period red LED29r and green LED29g lights by a predetermined time, blue LED29b is lit during the sensing period (see Figure 10).

Hereinafter will be described the effects of the liquid crystal display device 20 according to the present embodiment. As described above, when the liquid crystal panel 11 in CG silicon, the light reception sensitivity of the photodiodes 6 is high for blue light, low in the red or green light. Therefore, when turning on the blue LED29b during the sensing period than when is lit red LED29r or green LED29g, the light reception sensitivity of the optical sensors 2 is high. It the light reception sensitivity of the optical sensors 2 is high, although not preferred for detecting a shadow image of the object, in order to detect a reflection image of the object is preferable.

Therefore, the liquid crystal display device 20, in the sensing period of the reflection image mode, with priority to light the high light reception sensitivity blue light source of the optical sensor 2 (blue LED29b). Thus, in the sensing period of the reflection image mode, the amount of light detected by the optical sensors 2 increases, while suppressing the power consumption of the backlight 24, and the clarity of the reflected image, the touch position of the reflection image mode it is possible to improve the detection accuracy. The liquid crystal display device 20, in the sensing period of the reflection image mode, with priority to light the light-receiving sensitivity is low the color of the light source of the optical sensor 2 (red LED29r and green LED29g). Thus, in the sensing period of the shadow image mode, the amount of light detected by the optical sensor 2 is reduced to reduce the influence of backlight light upon detecting a shadow image, obscuring the reflection image, shadow image mode it is possible to increase the detection accuracy for a touch position.

The liquid crystal display device 20 in three LED29r, 29g, 29b is set to be turned by a predetermined time order within one frame time, may be simultaneously lit two or more LED, and three types of LED all may be turned off at the same time. In general, the light reception sensitivity of the optical sensors in the sensing period of the reflection image mode is lit with priority high color light sources, the lighting light receiving sensitivity of the optical sensor with priority lower color of the light source in the sensing period of the shadow image mode by while suppressing the power consumption of the backlight, it is possible to increase the detection accuracy for a touch position. Thus in accordance with the receiving characteristics of the optical sensor, by controlling the lighting state of a plurality of colors of light sources that constitute a backlight, and suitably controlled in accordance with the light reception sensitivity of the optical sensors on the situation, the detection accuracy for a touch position it can be increased.

(Third Embodiment)
Figure 12 is a block diagram showing a configuration of a liquid crystal display device according to a third embodiment of the present invention. The liquid crystal display device 30 shown in FIG. 12, those liquid crystal display device 10 according to the first embodiment to remove the illuminance sensor 17 (FIG. 1) to replace the image processing unit 16 and MPU18 to the image processing unit 36 ​​and MPU38 it is. Among the elements in this embodiment, the same components as those of the first embodiment, its description is omitted with the same reference numerals.

Display data Din inputted to the liquid crystal display device 30 is supplied via the image processing unit 36 ​​to the panel driving circuit 12. The image processing unit 36 ​​stores one frame of the display data Din, 1 ratio of blue component included in the display data Din for one frame (hereinafter, referred to as blue content) sought, blue content rate data indicating blue content and outputs the BX. MPU38, when selecting an operating mode, using a blue content rate data BX instead of illumination data LX. The image processing unit 36 ​​is included in the display data Din, the light receiving sensitivity of the optical sensor 2 functions as a characteristic detecting unit to determine the amount of high color.

Figure 13 is a flowchart showing a touch position detection process performed by the liquid crystal display device 30. The process shown in FIG. 13, the image processing unit 36 ​​and the MPU38 performed every frame time. First, the image processing unit 36 ​​obtains a blue content rate of display data Din, and outputs blue content rate data BX (step S31). Then, MPU 38, based on blue content rate data BX, selects the operation mode MD (step S32). In step S32, shadow image mode is selected when blue content is less than the predetermined threshold value, the reflection image mode is selected when blue content is equal to or more than the threshold. Since step S33 and subsequent steps are the same as in the first embodiment, the description thereof is omitted here.

Hereinafter will be described the effects of the liquid crystal display device 30 according to the present embodiment. As described above, when the liquid crystal panel 11 in CG silicon, the light reception sensitivity of the photodiodes 6 is high for blue light, low in the red or green light. Therefore, when there are many blue component to the display data Din is the light reception sensitivity of the optical sensors 2 is high. It the light reception sensitivity of the optical sensors 2 is high, although not preferred for detecting a shadow image of the object, in order to detect a reflection image of the object is preferable.

Therefore, the liquid crystal display device 30 selects the shadow image mode when a low blue content of the display data Din, when a high blue content selecting a reflection image mode. Thus, easily detecting a shadow image when the amount of blue is small, when the amount of blue is large in consideration easily detecting a reflection image, by selecting a suitable operating mode based on the amount of blue backlight while suppressing the power consumption of 14, it is possible to increase the detection accuracy for a touch position.

The liquid crystal display device 30 shown in FIG. 12 is a modification of the liquid crystal display device 10 according to the first embodiment, by modifying the liquid crystal display device 20 according to the second embodiment, the same liquid crystal it is possible to construct a display device. It is also possible to provide an illumination sensor that detects the intensity of external light to these liquid crystal display devices. In the liquid crystal display device provided with an illumination sensor, the MPU, based on the illuminance data outputted from the blue content rate data and illuminance sensor output from the image processing unit, to select whether shadow image mode or the reflection image mode.

In the first to third embodiments, the liquid crystal panel 11 is set to the provision of the light sensor 2 for each pixel, it may be provided an optical sensor 2 for a plurality of pixels, provided in each sub-pixel it may be. Also, rather than a backlight 14 LED, for example, a cold cathode tube (CCFL: Cold Cathode Fluorescent Lamp) may be constituted by such. Further, when the liquid crystal panel 11 is amorphous silicon, the light reception sensitivity of the photodiodes 6 is high for red light and is low in green light or blue light. Therefore, in this case, may be configured the same liquid crystal display device and the first to third embodiments are replaced with blue and red. It is also possible to configure the display device other than the liquid crystal display device in the manner described above.

Display device of the present invention, while suppressing the power consumption of the backlight, because it has a feature that it is possible to increase the detection accuracy for a touch position, such as a liquid crystal display device having a plurality of optical sensors on the liquid crystal panel, various it can be utilized to display device with a photosensor having a backlight.

Claims (11)

  1. A display device comprising a plurality of optical sensors,
    A display panel including a plurality of pixel circuits and a plurality of optical sensors which are arranged two-dimensionally,
    A drive circuit that drives the display panel,
    A backlight that irradiates light on the back of the display panel,
    When detecting a reflection image of the object, said light sensing period for reading the signals from the sensor, the backlight so that the amount of light detected by the light sensor than the display period for writing a signal to the pixel circuit is increased and a backlight control unit for controlling the display device.
  2. Or shadow image mode that detects a shadow image of the object, further comprising an operation mode selection unit for selecting whether the reflection image mode that detects a reflection image of the object,
    The backlight control unit, when the reflection image mode is selected, and controls the backlight so much the amount of light detected by the light sensor than the display period during the sensing period, the display device according to claim 1.
  3. The backlight control unit, when the reflection image mode is selected, the sensing period and controls the backlight such that the luminance is higher than the display period, the display device according to claim 2.
  4. The backlight control unit, when the shadow image mode is selected, the sensing period and controls the backlight such that the luminance is lower than the display period, the display device according to claim 3.
  5. The backlight includes a plurality of colors of light sources,
    The backlight control unit, and controls the lighting state of the light source based on the light properties of the light sensor, the display device according to claim 2.
  6. The backlight control unit, when the reflection image mode is selected, a sensing period, characterized in that it is turned with priority color of the light source a high light reception sensitivity of the optical sensor, the display device according to claim 5 .
  7. The backlight control unit, when the shadow image mode is selected, a sensing period, characterized in that it is turned with priority color of the light source the light receiving sensitivity is low the light sensor, the display device according to claim 6.
  8. Further comprising an illuminance sensor for detecting the illuminance of outside light,
    The mode selecting unit, based on the illuminance detected by the illuminance sensor, and selects whether shadow image mode or the reflection image mode, the display device according to claim 2.
  9. Further comprising a characteristic detecting unit that obtains a characteristic of display data supplied to the display panel,
    The mode selecting unit, based on the determined characteristics in the characteristic detector, and selects whether shadow image mode or the reflection image mode, the display device according to claim 2.
  10. The characteristic extraction unit, as a characteristic of the display data, and obtains the amount of light sensitive color of the light sensor, the display device according to claim 9.
  11. A display panel including a plurality of pixel circuits and a plurality of optical sensors which are arranged two-dimensionally, a driving circuit for driving the display panel, a display device including a backlight that irradiates light on the back of the display panel a driving method,
    Using the drive circuit, and writing the signal to the pixel circuit,
    A step of using said drive circuit reads the signal from the light sensor,
    When detecting a reflection image of the object, said light sensing period for reading the signals from the sensor, the backlight so that the amount of light detected by the light sensor than the display period for writing a signal to the pixel circuit is increased and a step of controlling the driving method of the display device.
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US8411117B2 (en) 2013-04-02 grant
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